We give a complete algebraic classification of nilpotent binary Lie algebras of dimension at most 6 over an arbitrary base field of characteristic not 2 and a complete geometric classification of nilpotent binary Lie algebras of dimension 6 over C. As an application, we give an algebraic and geometric classification of nilpotent anticommutative CD-algebras of dimension at most 6.Proof. Let θ ∈ Z 2 BL (A, F). Then A θ is a binary Lie algebra. We denote the Jacobian of elements x, y, z in A θ by J A θ (x, y, z). Now consider x, y, z, t ∈ A. (1.3),
By the identityt] , x, y) = 0; J([x, y] , z, t) + J([x, t] , z, y) + J([z, y] , x, t) + J([z, t] , x, y) = 0; we deduce that ψ θ ([x, y] , z, t) + ψ θ ([x, t] , z, y) + ψ θ ([z, y] , x, t) + ψ θ ([z, t] , x, y) = 0, as desired.